Power-operated machine tools have a rotating spindle for use in drilling, reaming and other material removing operations. The material that is being worked on needs to be held in place by the rotating spindle. A workholding chuck is the descriptive term commonly used in a wide variety of applications, where holding of a workpiece is needed. Workholding chucks can be mounted onto lathes or used in milling machines. The actuation (clamping and un-clamping) of the chuck can be accomplished by an external force, such as on a lathe by using its internal drawbar, or by incorporating an internal piston into the chuck.
A current drawback of existing chucks is their lack of gripping range. Typically, a workholding chuck can grip a round part that varies by no more than 0.50″ to 1.00″ in diameter. More of a variation requires the chuck jaws to be manually moved.